Nothing says fall like taking a bite out of a fresh Honeycrisp apple, handpicked from one of Indiana's you-pick orchards.

But this autumn staple - along with the $31.2 billion contribution agriculture provides to the state's gross domestic product - faces an uncertain future because of the effects of climate change.

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A report released Tuesday by Purdue University's Climate Change Research Center details some of the challenges Hoosier farmers may face in the coming decades.

Among the findings:

*Corn and soybeans - the state's top commodities - will have declining yields.

*Warming may change which crops are able to grow in the state.

*Indiana's livestock will be put at an increased risk of heat stress, which may add costs to production.

*The positives of higher carbon dioxide concentrations and a warmer climate are largely offset by the negatives.

About 78 percent of Indiana's farmland goes to grow corn and soybeans, but warming temperatures and a decline in soil moisture are expected to decrease crop yields. Corn production, in particular, could decline by as much as 20 percent by the middle of the century.

Specialty crops will also be jeopardized by warming temperatures, according to the report.

"People who have apple orchards may need to consider planting different varieties going forward," said Jeff Dukes, director of the Purdue Climate Change Research Center.

"They've got to be thinking about future climate, not just today's climate, because it's going to shift during the lifespan of those trees."

Livestock will experience more instances of heat stress, and farmers will likely face increased costs associated with keeping animals cool with ventilation systems. Even the perceived benefits of a warming climate and higher carbon dioxide concentrations come with significant downsides, said Laura Bowling, a professor at Purdue and lead author on the report.

Springs will get warmer earlier, potentially lengthening the growing season. But wetter springs may actually keep farmers from getting on the field.

Changing weather patterns associated with an earlier growing season might also affect Indiana's specialty crops. Perennial plants such as apple trees and vines require cool, but not freezing, periods to bloom. If the plants bud before the last frost, the crop could be in danger of being lost for the year.

And while more carbon dioxide means plants will grow more efficiently, higher temperatures may "temper or negate those gains altogether."

"It's a double-edged sword," Bowling said.

There's also evidence that exposure to higher carbon dioxide levels leads to a decrease in plant protein and mineral content, the report said, making food less nutritious. The exact effects of this phenomenon on livestock and humans are still not well understood.

These effects could have a substantial effect on the sector that provides 5 percent of the state's gross domestic product. The intense drought of 2012 led to huge losses in corn yields and federal crop insurance payouts that totaled more than $1 billion. Three years later, heavy rains destroyed 5 percent of Indiana's corn and soybean crop, a monetary loss of $300 million.

While no single weather event can be attributed to climate change, research suggests that a warming climate will result in an increased frequency of these types of events.

One possible solution lies in soil health. A movement around adopting practices, particularly planting cover crops, that help prevent soil erosion and nutrient runoff has been gaining traction in the U.S.

"So much of our agriculture relies on our soil," said Dukes from Purdue. "There are going to be some major challenges for Indiana producers in the next few decades. One of the ways we can start preparing for them now is to make sure our soil is in good shape."

Indiana farmers are leading the country in some soil conservation techniques, a factor that could be important as rainfalls become more intense in the early spring. Intense rain increases nutrient loss and erosion on farm fields. In turn, conditions become drier towards the end of the growing season, which could lead to drought-like conditions, according to the report.

"A lot of people perceive droughts and floods to be opposites," Bowling said. "They're part of the same system."

Faced with these challenges, farmers and farm organizations are already trying to develop practices that will help them though harder times.

"There are a lot of farm groups that are trying to figure out ways to prepare people for climate change," said Thomas Driscoll, director of conservation policy at the National Farmers Union. Although NFU directly addresses climate change while advocating for provisions in the Farm Bill, he concedes that other groups have a harder time discussing this once controversial issue.

Instead, organizations are finding value in focusing on other aspects of conservation, some of which have a positive impact on the environment and farmers' bottom lines.

Precision agriculture, for example, can help farmers apply just the amount of fertilizer necessary, which can help reduce costs. Some soil health practices have also shown a long-term benefit of keeping soil nutritious while also making farms more resilient against flood or drought.

"Producers are always trying to adapt to what's going on," said Dennis Todey, director of the Midwest Climate Hub, one of several regional offices that launched in 2014 out of the USDA. The Climate Hubs provide farmers with information and resources around climate change and conservation.

"We talk about what's happening at the poles, which is important. We talk about the coasts. But there are things that are going to happen in the middle of the country," Todey said, "and we have to account for that."